Chemistry Multiple Choice Questions on “Solid State – Close Packed Structures”.
1. In ______ constituent particles are closely packed leaving the least amount of vacant spaces.
a) plasma
b) liquids
c) solids
d) gases
Answer: c
Clarification: In solids, the constituent particles tend to be closely packed due to strong forces between them. Hence, solids are stable and have a definite shape.
2. What is the coordination number for one-dimensional close packing?
a) 2
b) 1
c) 4
d) 6
Answer: a
Clarification: In one-dimensional close packing, the constituent particles are assumed to be arranged in a row. Thus, each constituent particle comes in contact with 2 of its neighbors and thereby giving the coordination number 2.
3. In how many ways, can the two-dimensional close packed structure be generated?
a) 3
b) 2
c) 1
d) 5
Answer: b
Clarification: Two-dimensional close packed structure can be generated using the one-dimensional close packed structures. This can be done in 2 ways:
• By placing one row of one-dimensional structure below another in such a way that the spheres are one below the another.
• By placing one row of one-dimensional structure below another such that spheres of second row fit in the depressions of the first row.
4. What is the coordination number for a two-dimensional square close packed structure?
a) 8
b) 4
c) 6
d) 2
Answer: b
Clarification: In a two-dimensional square close packed structure, each sphere is in contact with 4 of its adjacent spheres. Hence, it has coordination number 4.
5. What is the coordination number for a two-dimensional hexagonal close packed structure?
a) 4
b) 8
c) 12
d) 6
Answer: d
Clarification: In a two-dimensional hexagonal close packed structure, each sphere is in direct contact with 6 of its adjacent spheres. Hence, it has coordination number 6.
6. Voids in two-dimensional hexagonal close packed structure are ___________ in shape.
a) circular
b) rectangular
c) triangular
d) hexagonal
Answer: c
Clarification: Two-dimensional hexagonal close packed structure are formed when one row of a one-dimensional structure is placed below another in such a way that spheres of second row fit in the depressions of the first row and thereby creating triangular voids between them.